Here is the start of an inventory of the extra features that dash and its builtins have over POSIX.1-2017.
- Supports local scope of variables and options via a
localbuiltin (from original Ash in 1989). - Supports (in some builds) some
-V/-Eoptions as aliases for-o vi,-o emacs. - Supports a
-p/-o privilegedoption. - A
-loption to start as login shell -Ias alias to-o ignoreeof- its
echosupports the-noption - its
readsupports a-p promptoption - its
printfsupports%f/e/E/g/G. - its
[/testsupport-ef,-nt,-ot,<,> - its
ulimitsupports many more options that those specified by POSIX - handling of
MAIL,MAILCHECK,MAILPATHvariables.